Communication systems are known to employ power control methods which control transmission energy of remote units. Once such communication system employing power control is a spread-spectrum communication system. Power control in a spread-spectrum system serves two main functions. Firstly, because each remote unit's signal in a spread-spectrum system is typically transmitted on the same frequency, a majority of the noise (which is inversely proportional to bit energy per noise density i.e., E.sub.b N.sub.0 which is defined as the ratio of energy per information-bit to noise-spectral density), associated with a received signal can be attributed to other remote units' transmissions. The magnitude of noise is directly related to the received signal power of each of the other remote units' transmissions. Thus it is beneficial for a remote unit to transmit at the lowest power level possible. Secondly, it is desirable to dynamically adjust the power of all remote units in such a way that their transmissions are received by the base station with approximately the same power level. To accomplish this, it is necessary for the closest transmitters to reduce their power by as much as 80 dB when compared to the power of the furthest transmitters.
The current method of controlling reverse channel power in a code-division, multiple-access (CDMA) communication system is described in Cellular System Remote Units-Base Station Compatibility Standard of the Electronic Industry Association/Telecommunications Industry Association Interim Standard 95 (TIA/EIA/IS-95A), which is incorporated by reference herein. (EIA/TIA can be contacted at 2001 Pennsylvania Ave. NW Washington D.C. 20006). As described in TIA/EIA/IS-95A, a power-control group is transmitted from the remote unit and received by the base station. The base station compares the energy of the power-control group to a threshold and instructs the remote unit to power up or down accordingly by transmitting a power-adjustment command to the remote unit. While this algorithm does insure that the threshold level does not contribute to long runs of frame errors where the remote unit is not transmitting at a high enough power level, the power level of the remote unit can be higher than necessary for lengthy periods of time, needlessly contributing to system noise.
Thus a need exists to reduce noise in a CDMA system by dynamically adjusting the step-down size of the power-control threshold.